Making Views Self-Maintainable for Data Warehousing

Abstract

A data warehouse stores materialized views over data from one or more sources in order to provide fast access to the integrated data, regardless of the availability of the data sources. Warehouse views need to be maintained in response to changes to the base data in the sources. Except for very simple views, maintaining a warehouse view requires access to data that is not available in the view itself. Hence, to maintain the view, one either has to query the data sources or store auxiliary data in the warehouse. We show that by using key and referential integrity constraints, we often can maintain a select-project-join view when there are insertions, deletions, and updates to the base relations without going to the data sources or replicating the base relations in their entirety in the warehouse. We derive a set of auxiliary views such that the warehouse view and the auxiliary views together are self-maintainable--they can be maintained without going to the data sources or replicating all base data. In addition, our technique can be applied to simplify traditional materialized view maintenance by exploiting key and referential integrity constraints.